An ELT Glossary : Voicing

• Definition : An unvoiced sound is one produced without vibrating the vocal cords while the sound is being made, while a voiced sound includes vibration of the vocal cords. If you touch your larynx at the same time as saying /m/ or /i/ you should be able to feel the vibration, whereas if you say /s/ or /ʃ/ you won't.

• Example : Many of the English consonants come in pairs which are identical in terms of place and manner of articulation - eg  /p/ and /b/ are both bilabial plosive consonants - they are made by momentarily blocking the airflow by closing the lips. But  /b/ is voiced - when it is made made the vocal cords are vibrated - while /p/ is unvoiced.